Thermal inkjet hardcopy devices such as printers, graphics plotters, facsimile machines and copiers have gained wide acceptance. These hardcopy devices are described by W. J. Lloyd and H. T. Taub in "Ink Jet Devices," Chapter 13 of Output Hardcopy Devices (Ed. R. C. Durbeck and S. Sherr, San Diego: Academic Press, 1988) and U.S. Pat. Nos. 4,490,728 and 4,313,684. The basics of this technology are further disclosed in various articles in several editions of the Hewlett-Packard Journal [Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 45, No.1 (February 1994)], incorporated herein by reference. Inkjet hardcopy devices produce high quality print, are compact and portable, and print quickly and quietly because only ink strikes the paper.
An inkjet printer forms a printed image by printing a pattern of individual dots at particular locations of an array defined for the printing medium. The locations are conveniently visualized as being small dots in a rectilinear array. The locations are sometimes "dot locations", "dot positions", or pixels". Thus, the printing operation can be viewed as the filling of a pattern of dot locations with dots of ink.
Inkjet hardcopy devices print dots by ejecting very small drops of ink onto the print medium and typically include a movable carriage that supports one or more printheads each having ink ejecting nozzles. The carriage traverses over the surface of the print medium, and the nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed.
The typical inkjet printhead (i.e., the silicon substrate, structures built on the substrate, and connections to the substrate) uses liquid ink (i.e., dissolved colorants or pigments dispersed in a solvent). It has an array of precisely formed orifices or nozzles attached to a printhead substrate that incorporates an array of ink ejection chambers which receive liquid ink from the ink reservoir. Each chamber is located opposite the nozzle so ink can collect between it and the nozzle. The ejection of ink droplets is typically under the control of a microprocessor, the signals of which are conveyed by electrical traces to the resistor elements. When electric printing pulses heat the inkjet firing chamber resistor, a small portion of the ink next to it vaporizes and ejects a drop of ink from the printhead. Properly arranged nozzles form a dot matrix pattern. Properly sequencing the operation of each nozzle causes characters or images to be printed upon the paper as the printhead moves past the paper.
The ink cartridge containing the nozzles is moved repeatedly across the width of the medium to be printed upon. At each of a designated number of increments of this movement across the medium, each of the nozzles is caused either to eject ink or to refrain from ejecting ink according to the program output of the controlling microprocessor. Each completed movement across the medium can print a swath approximately as wide as the number of nozzles arranged in a column of the ink cartridge multiplied times the distance between nozzle centers. After each such completed movement or swath the medium is moved forward the width of the swath, and the ink cartridge begins the next swath. By proper selection and timing of the signals, the desired print is obtained on the medium.
Color inkjet hardcopy devices commonly employ a plurality of print cartridges, usually either two or four, mounted in the printer carriage to produce a full spectrum of colors. In a printer with four cartridges, each print cartridge contains a different color ink, with the commonly used base colors being cyan, magenta, yellow, and black. In a printer with two cartridges, one cartridge usually contains black ink with the other cartridge being a tri-compartment cartridge containing the base color cyan, magenta and yellow inks. The base colors are produced on the media by depositing a drop of the required color onto a dot location, while secondary or shaded colors are formed by depositing multiple drops of different base color inks onto the same dot location, with the overprinting of two or more base colors producing the secondary colors according to well established optical principles.
For many applications, such as personal computer printers and fax machines, the ink reservoir has been incorporated into the pen body such that when the pen runs out of ink, the entire pen, including the printhead, is replaced.
However, for other hardcopy applications, such as large format plotting of engineering drawings, color posters and the like, there is a requirement for the use of much larger volumes of ink than can be contained within the replaceable pens. Therefore, various off-board ink reservoir systems have been developed recently which provide an external stationary ink supply connected to the scanning cartridge via a tube. The external ink supply is typically known as an "off-axis," "off-board," or "off-carriage" ink supply. While providing increased ink capacity, these off-carriage systems also present a number of problems. The space requirements for the off-carriage reservoirs and tubing impact the size of the printer, with consequent cost increase.
These various problems include undesirable fluctuations in ink pressure in the print cartridge, an unreliable and complex fluid seal between the print cartridge and the external ink supply, increased printer size due to the external ink supply's connection to the print cartridge, blockage in the ink delivery system, air accumulation in the tubes leading to the print cartridge, leakage of ink, high cost, and complexity.
More importantly, the new off-axis design print cartridges have very little internal ink capacity in their reservoirs. Each time a new cartridge is manufactured, it needs to be run through an automated print quality tester (APQT). This allows the manufacturer to screen out cartridges failing to meet minimum quality standards. This testing requires the use of ink. Additional production line processes that use ink may include a nozzle down flush, wetfiring, and reprinting. With the new off-axis cartridge designs, the amount of ink available internally may not be enough to make it through the APQT test and other uses of ink.
Prior to printer installation, the cartridge is in transit and in storage. Therefore, there is also a need to provide a means of lubricating and protecting the inlet port. In particular, the port should be protected from drying, leaking ink, and air ingestion.
What is needed is an fluidic coupling that releasably and fluidically connects to the inlet port of a print cartridge for ink replenishment so as to provide a print cartridge seal from the outside atmosphere, compliance, and an auxiliary ink source for the print cartridge.